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146                            GIANT EXTINCT FORMS                           CHAP.
gonia are represented to-day by a small Marsupial which has
been rediscovered within the last two or three years. This little
animal, formerly called Hyracodon (a pre-occupied name), is now
termed Caenolestes, and is a native of Colombia and Ecuador.
There are two species, and of these O. obscurus is called by
fche inhabitants " Baton runcho," which means opossum-rat. It
lives apparently upon bird's eggs and small birds, though it
belongs to the Diprotodont division of the Marsupials. Caenolestes,
however, although diprotodont, has not the syndactylous character
of the digits of the feet already referred to in the Kangaroos and
their allies. The pouch is small and rudimentary. The denti-
tion is I-f- O-J- Pm -|M|- = 46, and the teeth are said by Mr.
Thomas to be much like those of the Australian Dromicia.^
In the skull a peculiarity which does not bear upon its
affinities to other Marsupials, but is still interesting, is mentioned
by Mr. Thomas. The nasals are not sufficiently prolonged to
meet the upper edge of the maxillae, and so a vacuity is left, as
in the skulls of many Ruminants (e.g. the Sable Antelope). The
palate is very imperfect; the foramina, which render it so, reach
as far forward as the last premolar. The lower jaw has quite
the appearance of that of a Macropus or Phcdanger, with long
and forwardly projecting incisors.
Extinct Diprotodonts.—The great Diprotodon is a creature
with a skull a yard long, which must have been of the size of a
large Rhinoceros. Though closely allied to Macropus, it seems
that this great beast did not hop after the fashion of a Kangaroo,
its limbs being of a more equal size than in the Kangaroo.
Recently some further remains of Diprotodon have been discovered
in a lake known as Lake Mulligan, where they had apparently
been bogged. Professor Stirling has contributed an account of
these remains, which fills up a considerable gap in our knowledge.
He has been, able to state fche structure of the fore- and hind-limbs.
Both limbs are pentadactyle, the fingers of the fore-limb being
approximately equal in length and general development. In the
hind-limb the hallux is small, and consists of the metatarsal only.
This bone is fixed in the position of "extreme abduction/' and is
suggestive of an arboreal limb. Digits two and three may have
1 Thomas, f * On, CaenoltsUs, a still existing survivor of the Epanortludae of
Anaeghino, and the representative of a new family of recent Marsupials,"